Study On Comparing Of Photosynthetic Characteristics And Freezing Resistance Of Ulmus Pumila Cv.Jinye And Ulmus Pumila

In order to provide a theoretical basis for Ulmus pumila cv.jinye and Ulmus pumila in conservation management and introduction cultivation,separation and identification of pigment composition , leaf pigment content, photosynthesis - light response curve, photosynthetic parameters, diurnal variation of photosynthesis and leaf pigment content and leaf anatomy with three different shading treatments in leaf of Ulmus pumila cv.jinye and Ulmus pumila were searched. At the same time, the relative electrolyte leakage percentage , relative leakage of K+ and growth to resume of Ulmus pumila cv.jinye , Ulmus pumila,s sticks under low temperature treatments were studied pilotly in this paper. Purpose of the researchs was to provide evidences to promote the application and cultivation of Ulmus pumila cv.jinye and Ulmus pumila. The main findings were summarized as follow:(1)Extracts of leaf of Ulmus pumila, Ulmus pumila cv.jinye green and yellow were seperated. The seperating result was five,six and seven clear bands which identified and analysed by thin一layer scanning. The results were that descending order wasβ-carotene, pheophytin, lutein, chlorophyll a and chlorophyll b of extracts of leaf of Ulmus pumila according to Rf value; Descending order wasβ-carotene, pheophytin, lutein, lutein 1,chlorophyll a and chlorophyll b of extracts of leaf of Ulmus pumila cv.jinye green according to Rf value; Descending order wasβ-carotene, pheophytin, lutein, lutein 1, lutein 2,chlorophyll a and chlorophyll b of extracts of leaf of Ulmus pumila cv.jinye yellow according to Rf value.(2)The total contents and every kind of content of pigments in the leaves of Ulmus pumila cv.jinye were obviously lower than that of Ulmus pumila. Chlorophyll content of Ulmus pumila leave was 2.20 times of Ulmus pumila cv.jinye green leave, 4.38 times of Ulmus pumila cv.jinye yellow leave.But the contrary content of carotene was obviously higher than that of Ulmus pumila,it was the root causes that Ulmus pumila cv.jinye leave was yellow. Among which, chlorophyll content was 3 times of carotene in Ulmus pumila cv.jinye green leave,3.3 times in Ulmus pumila,2.2 times in Ulmus pumila cv.jinye yellow leave.(3)In Ulmus pumila cv.jinye yellow leave, chlorophyll a / b value was 1.75 times of Ulmus pumila. It was the main underlying reasons that converting light to chemical energy was better than Ulmus pumila of that.Stomatal conductance, transpiration rate and intercellular carbon dioxide concentration of Ulmus pumila cv.jinye were higher than that of Ulmus pumila,which was important environmental factors.(4)LCP of Ulmus pumila was 61.3μmol·m-2·s-1,LCP of Ulmus pumila cv.jinye was 71.2μmol·m-2·s-1,LSP of Ulmus pumila cv.jinye was 1013μmol·m-2·s-1,LSP of Ulmus pumila was 1276μmol·m-2·s-1. Compared with Ulmus pumila, Ulmus pumila cv.jinye higher LCP and lower LSP showed that it was relatively narrow range of adaptation and the lower demand for light than Ulmus pumila, it was favorable for expression of their color.(5)Diurnal variation of photosynthetic rate of Ulmus pumila cv.jinye the overall trends was no significant differences in both single-peak curve with Ulmus pumila. But the absolute value of photosynthetic rate of Ulmus pumila cv.jinye was significantly lower than that of Ulmus pumila. In the photosynthetically active radiation were about 1000μmol / (ms), Pn of Ulmus pumila was 1.7 times of that of Ulmus pumila cv.jinye.(6)Between different treatments, with the increasing of shading, each Pigment content of Ulmus pumila was decreased.There was max content at full-light conditions,and the min at 95%; with the increasing of shading, each Pigment content of Ulmus pumila cv.jinye was increased basically and was opposite trend.(7)with the increasing of shading,depth of leaves and palisade tissue of Ulmus pumila were thinning and depth of sponge tissue was increasing the thickness; depth of leaves of Ulmus pumila cv.jinye did not change significantly. At full-light conditions, sponge tissue was relatively developed, but palisade tissue was not.(8)The relative electric conductivity and relative leakage of K+ increased as S-curves with the temperature decreased. The first time, the semi-lethal temperature(LT50) for Ulmus pumila and Ulmus pumila cv.jinye,s one-year sticks was - 33.1℃,-33.7℃and-31.2℃,-30.3℃. It was in agreement with the recover test result. This method was simple, effective and reliable.